Excavation machines such as backhoe loaders, haul trucks, wheel loaders, scrapers, and other types of heavy equipment, are used to perform a variety of tasks. Some of these tasks involve carrying large, awkward, loose, and/or heavy loads along rough and crowded roadways. And because of the size of the machines and/or poor visibility provided to operators of the machines, these tasks can be difficult to complete effectively. For this reason, some machines are equipped with perception systems that provide views of a machine's environment to the operator.
Conventional perception systems include one or more perception sensors, such as LIDAR (light detection and ranging) devices, that capture different images, which are then combined to form a surround view. To combine the images, poses of the perception sensors need to be determined. For this purpose, a rate sensing device can be used to provide pose information at the location of each perception sensor. The pose information may include for example, one or more of position, orientation, linear velocity, angular velocity, and acceleration. The rate sensing device may include one or more rate sensors and may be, for example, an inertial measurement unit (IMU) or a visual odometry device. Such a perception system could measure and compensate for, e.g., vibration or movement of the perception sensors, to provide better results for the perception.
The rate sensing devices, however, are not ideal, and may have noises, bias, or drifts due to, for example, aging and temperature. The noises, bias, and drifts of the rate sensing devices may accumulate, affecting the accuracy of the determined pose of the perception sensors. In conventional technology, a state update source is used to update the readings of the rate sensing devices. The state update source can be a global navigation satellite system (GNSS), such as a global positioning system (GPS). The state update source can also be another system that is capable of providing state update, such as a pseudolite system, a perception based positioning system, a ranging radio system, a speedometer, an inclinometer, or an accelerometer. Such a configuration is not only used in perception systems, but may also be used in other systems using rate sensing devices, such as IMUs.
U.S. Pat. No. 8,457,891 of Vallot et al., which issued on Jun. 4, 2013 (the '891 patent), discloses a navigation system using an IMU for navigating a vehicle and a GPS to correct accumulating errors from the IMU. However, in such a conventional perception system, when GPS signal is not available, the readings of the IMUs cannot be updated. In this scenario, local disturbances may affect the result of the perception.
The disclosed system is directed to overcoming one or more of the problems set forth above and/or other problems of the prior art.